Actuating mechanism for coke oven door locking screws



C. OTTO July 8, 1941.

ACTUATING MECHANISM FOR COKE QVEN DOOR LOCKING SCREWS Filed July 16, 1938 '3 Sheets-Sheet 1 INVENTOR CARL 0770 'July 8, 1941. c. OTTO 2,248,187

ACTUATING MECHANISM FOR COKE OVEN DOOR LOCKING SCREWS Filed July l6, 1958 3 Sheets-Sheet 3 n INVENTOR BY W 2/ ATTORNEY Patented July 8, 1941 ACTUATING lWECHANISM FOR COKE. OVEN DOOR LOCKING SCREWS Carl Otto, The Hague, Netherlands, assignor to Fuel Refining Corporation,

poration of Delaware Dover, Del., a cor- Application July 16, 1938, Serial No. 219,534 2 Claims. (01. 202-248) Such a self-sealing coke oven door is customarily secured in its closed position by means of upper and lower locking bars, each connected toa rigid portion of the door by'a supporting spindle passing through the locking bar and in threaded engagement either with the locking bar, or with the door structure, so that the locking bar may be moved away from the rigid portion of the door in the door locking operation, by rotating the spindle in one direction, and by a reverse rotation, may be moved toward the rigid door portion in the door unlocking operation. In the closed and locked position of the door, each end of each locking bar engages and pressesoutwardly against a' retaining device which ordinarily is a hook extension from thedoor' frame.

To resist the outward thrust against the door, of the charge in a large-coking chamber, and to resist the occasional excess of gas pressure in the coking chamber over the atmospherical pressure, and to bendthe sealing member as required to bring the sealing edge into contact with the door frame sealing surface, notwithstanding door and door frame deformations occurring in use, and to cut through pitch or other material depositing on the sealing surface or sealing edge, and to cut through coke or coal particles, which may be caught between the sealing edge and the sealing surface, requires a locking force acting between the rigid portion of the door and each lockin bar, which amounts to thousands of pounds, and in, some cases, may well be ten or twelve tons. The rotation of one element of a threaded connection transmitting a force of any such magnitude can only be effected manually through long, powerful, and consequently heavy, wrenches, and is especially diflicult because the upper lockin bar may be a dozen feet or more above the bench at the side of the battery on which the door handling attendant ordinarily must stand.

While the idea of a power actuating mechanism for rotating the locking bar spindles to lock and unlock self-sealing coke oven doors is not novel, having been disclosed by me in German Patent No. 541,251,-dated June 5, 1931, it is still the usual practice to lock and unlock such doors by manual rotation of a threaded locking bar spindle. The present invention was devised with the primary idea of improving the patent, and providing such mechanism with certain safety provisions not disclosed in said prior patent. I r

) One specific object of the present invention is to provide a power actuated mechanism, adapted to subject the locking bar spindle to a turning torque in the unlocking direction, which i higher than that required, or provided, for the rotation of the spindle in the door locking operation, so as to thereby eliminate risk of unduly prolonged delay in removing a coke charge from an oven, as the result of insufficient power in the mechanism to unlock the door, when a considerable increase in the frictional resistance to the unlocking movement of the spindle develops, as it may occasionally, during a coking operation.

Another specific object of the invention is to include in the spindle rotating mechanism, provisions which are automatically effective to prevent an unnecessarily prolonged operation of the mechanism in the door unlocking direction from having injurious consequences. The means devised by me for the attainment of the last mentioned object comprises variousforms. In one form of said means, the unlocking operation is terminated after and as a direct result of a predetermined extent of such operation. In another form, the unlocking operation is automatically terminated at the end of a predetermined time period following the initiation of'the operation. In a third form, the nut and screw parts of the threaded connection through which the rotation of the locking bar spindle locks and unlocks the door, are moved out of threaded engagement with one another by an unlocking operation in excess of a predetermined amount, and are adapted to operatively reengage as soon as the mechanism is operated in the door locking direction. r

The various features of novelty which characterize my invention-are pointed out with particularity in the'claim annexedto and forming a part of this specification. For a better understanding of the invention, however, its advantages, and specific objects attained with its use, reference should be had to the accompanying drawings and descriptive matter in which I'have illustrated and described preferred embodiments of the invention.

Of the drawings:

mechanism of said prior- Fig. 1 is a fragmentary elevation, with parts broken away and in section, of a door spindle rotating mechanism in operative relation with a coke oven door in its closed position;

Fig. 2 is a horizontal section taken on the line 22 of Fig. 1;

Fig. 3.is.a section on the line 3-3 of Fig. 2;

Fig. 4 is a motor energizing and control circuit diagram;

Fig. 5 is a sectional elevation illustrating a modification;

Fig. 6 is a section on the line 66 of Fig. 5;

Fig. 7 is a sectional elevation illustrating another modification;

Fig. 8 is a section on the line 88 of Fig. 7; Fig. 9 is a view, partly in section, illustrating a third modification.

In Figs. 1 and 2, I have illustrated a preferred embodiment of my improved door spindle rotating mechanism, positioned for operating engagement with the two threaded spindles, each supporting a locking bar, of a self-sealing coke oven door of a well known and extensively used type, mounted'in the doorway of-a coke oven structure of conventional type. That structure, as shown, comprises a heavy cast metal door frame A, which-extends into, and forms a lining for the mouth or end of a coking chamber B. The door frame A is formed with a sealing surface A, whichis transverse to the axis of the oven chamberg-faces outwardly, and extends all the way around the doorway.

--'I'he coke oven door shown in Figs. 1 and 2, includes a rigid outer metallic section C, shown as comprising two oppositely facing channel bars rigidly connected by cross bar parts. Two of those parts, D- and DA located at upper and lower levels and similar -to one another serve as locking-bar spindle supports. Each of the parts I) and DA has a central hub portion formed with a threaded passageway D, extending in the axial direction of the door midway between the side edges of the latter and into which the corresponding locking bar spindle E is threaded. Socalled clamping screws F, are threaded through the inner flange portions 0', of the outer door section C into engagement with, and are adapted to adjust the adjacent portions of the flexible sealing section" G of the door toward and away from the other section C, as required for the establishment of gas tight seal between the member- G and the sealing surface A. The sealing member G- is shown as comprising a flexible metallic body plate extending across the door- -way, in.the closed'posi-tion of the rim portion g extending inwardly away from said plate-at the margin of the latter, with the inner edge of the portion g directly engaging the sealing surface A of the door frame, in the closed position of. the door. The rim portion g is shown as formed by one flange of a bar of an angle bar section, having its other flange alongside, and bolted, or riveted, to the flexible body plate portion of the sealing member. The door comprises an inner refractory plug section II, and the door sections C, G and H may be mechanically connee-ted in any usual or suitable manner.

Each of the two threaded spindles or supporting bolts E of the door has a corresponding locking bar'I journalled on its outer end portion. In the normal closed condition of the door, each bar is horizontally disposed, and is in engagement with door retaining hook members J bolted or otherwise secured to the door frame-member A. As shown, one of door, and a 3- the two hooks J adapted 75 the hub D for engagement by a single locking bar I, faces upwardly and the other faces downwardly, so that the locking bar may be turned about its supporting spindle into and out of engagement with the corresponding hooks J.

As shown in Figs. 1 and 2, each spindle E is provided with a thrust collar E. which engages a bearing surface provided at the inner side of the corresponding locking bar I, so that when the spindle E is rotated in the direction to move and collar E apart and the locking bar I is in engagement with the hooks J, the spindle will be held against bodily movement in the direction of its length, and the adjacent portion of the door will be moved toward the coke oven structure forcing the adjacent portion of the sealing edge 9 against the sealing surface As shown, the spindle E is provided with a collar E at the outer side of the corresponding locking bar provided to prevent accidental displacement of the locking bar, when the latter is not held in operative relation with the door by the sealing pressure.

As those skilled in the art will understand, the coke oven door structure illustrated, is commercially used, and is illustrated herein as one example ;of the numerous self-sealing door types and forms with which the present invention may beused with advantage.

For its rotation with the form of mechanism illustrated herein, each locking bar spindle E is provided at its outer end with suitable, oppositely disposed, transversely extending lever arms E shown as formed by the opposite end portions of a bar having a central socket which receives the outer end of the spindle E, and in which the latter is secured against rotation relative to the bar, as by making the end of the shaft and the socket square in cross-section.

In the form of embodiment of the invention illustrated in Figs. 51, 2 and 3, a verticallydisposed, beam-li-ke, door machine .part K, supports similar upper and lower spindle rotating mechanisms L, 50 relatively positioned that they may be brought into simultaneous operation relative with the upper andlower locking bar spindles E of a coke oven door *likethat shown in Fig. 1. The door machine part K may also serve as the door lifting and supporting element of the door machine. To that end, the .part K is provided with door engaging parts, which may be of customary form, and are shown as comprising a lower spring pressed abutment or door positioning member M, andan upper door lifting hook member N adapted to engage the usual bracketlike part 0 provided on 'the door for the purpose, when the part N is given a clockwise door lifting movement. As shown, when the member N turns engagement with the door part 0, a lever NA to tilt the upper locking bar I about its supporting spindle E and thereby moves the ends of the bar out of engagement with the hooks J. The tilting movement thus given the upper bar I is transmitted to the lower bar I, in the usual manner, by means of a link P connecting the two bars, said means also gives the bars a gravitational bias for' turning movement back into engagement with the retaining hooks J, when, in the final portion of the door replacing operation, the member N is lowered to transfer the weight of the door from the door machine to the door frame. The door machine member K may be supported and given the vertical and horizontal movements required for the engagement and disengagement of the parts N and O, and to raise, lower and transport the door, in any usual or suitable manner, which need not be illustrated or described. herein.

As shown, each mechanism L comprises a housing or casing structure formed with a chamber L enclosing speed reducing gears, through which the main operating shaft l of the mechanism is driven. The shaft I is journalled in bearings 2 mounted in the front and rear walls of the chamber L, and at its front end carries spindle operating means adapted for engagement with the operating arms ll! of a locking bar spindle. As shown, the engaging means carried by the shaft I comprises a lever 3 rigidly secured to the front end of the shaft land provided, adjacent its ends, with pins 4, parallel to the shaft I, so that one may engage one edge of one, while the other engages the other edgeof the other arm E As shown, each pin 4 is axially movable in the lever 3, and is normally held in an advanced position by a corresponding spring 5.- If, when the mechanism L is advanced, the relative angular positions of the pins 4 and arms E are such that the pins 4 engage the outer sides of the arms E the advancing movement of the pins is temporarily arrested, but on subsequent angular movement of the lever 3, moving the pins 4 laterally of the arms E the pins are advanced by the springs 5 into position to engage the edges of'the arms E The pins 4 are advantageously long enough, and spaced widely enough apart, to operatively couple the locking bar spindle and shaft I, even though said spindle and shaft are appreciably out of axial alignment with one another, notwithstanding an appreciable variation in the horizontal displacement of the lever 3 from the lever arms E The mechanisms L may thus be used on door machines of the type in which the partK is adjusted to different vertical positions in the door locking and unlocking operations. a

As shown, the mechanism L includes a worm supporting drive shaft 6 which extends through an end wall of the chamber L', and is journalled in bearings I at the opposite ends of the worm. The'shaft 6 is connected by a coupling 8' to the shaft of an electric driving motor 8 mounted on the member K, and engages and rotates a worm gear 9 secured to a shaft Ill. The latter is journalled in the front and rear walls of the chamber L, and has a sprocket wheel II secured wit. The wheel I I is connected by a sprocket chain I2 to, and drives a sprocketwheel 13 secured to a shaft I4 also journalled in bearings mounted in the front and rear walls of the chamber L. The chain I2 also runs over a sprocket wheel I2, forming a part of a safety mechanism hereinafter described. Aspur gear I5 secured to the shaft I4, is in mesh with'a larger spur gear I6 secured to a shaft I'i, also having its ends journalled in bearing supported by the front and rear walls of the' chamber L. A rotatable element I8 journalled on the shaft H at the rear side of the gear I8, comprises a spur gear portion in mesh with a spur gear Ill-carried by and secured to the shaft I. .A second rotatable element 20 is journalled on the shaft I! at the front side of the gear I6, and comprises a spur gear portion in mesh with a spur gear 2I rigidly secured to the shaft I alongside the gear [9.

The members I8 and 28'may be connected al ternately, but never simultaneously, to the spur gear I6, ment as the latter, and in Figs; 2 and 3, means are provided soas to have the same angular movein the construction shown for automatically coupling the element I8 to the gear I6 when'the latteris rotated counterclockwise, as seen in Fig. 3, to look a door in place, and to automatically couple the element 20 to the gear I6, when the latter is rotated clockwise to unlock the door. The means shown for this purpose, comprises a rock shaft 22 parallel to the shaft I1 and extending throughand journalled in the gear I6, adjacent the periphery of the latter. Secured to the rear end of the shaft 22 is a pawl 23,'which when the gear is rotated in the counter-clockwise direction, as seen in Fig. 3, engages one or another of the ratchet teeth 24 of a ratchet gear portion of the element I8, so that the element I8 then rotates with the gear I6. At its opposite end, the shaft 22 has secured to it a pawl 25, which when the gear I6 rotates in the clockwise direction, engages one or another of ratchet teeth 26 of a ratchet wheel portion of the element 20, which is thereby caused to share the rotative movement of the gear I6.

Ordinarily, when the gear I6 starts into rotation in the counterclockwise direction, the 23 will .be out of position to engage a ratchet tooth 24, so that the element I8 will not be started into rotation immediately, but the pawls 23 and 25, have weight portions, 23' and 25, respectively, so disposed, that as the shaft 22 is turned counterclockwise about the shaft I1 away from its uppermost position, the pawl 23 will be gravitationally biased for movement into engagement with a corresponding tooth 24. Conver'sely, on the. clockwise rotation of the gear I6, if the pawl 25 is not initially in engagement with a ratchet. tooth 28, it will be turned into engagement therewith by the weights 23 and 25' as the shaft 22 turns away from its uppermost position.

The purpose of the arrangement for rotating the shaft I-in the door locking direction through the element I8, and in the door unlocking direction through the element 20, is to make the torque available for unlocking the door greater than that available for locking the door, so as to thereby decrease the risk that through accidental reduction in the available power, or increase in the resistance to the rotation of the spindles E, the mechanism will be unable to unlock a door when such unlocking is desirable. To thus vary the torque, the spur gears I9 and 2I and the spur gear portions of the elements I8 and 20, are so relatively proportioned that the gear ratio through which the element I8 rotates the shaft I, is higher than the ear ratio through which the member 20 rotates the shaft I. In the construction shown, the first mentioned ratio is a one to one ratio, while the second ratio is a one to two ratio, so that under normal operating conditions, the torque availablefor unlocking the door is double that avail-.

able for locking the door.

The safety mechanism sprocket wheel I2 is journalled in a lever 39. The lever 38 is pivotally supported at one end by the shaft I4, and is connected at its other end to a vertically disposed .link 3|, which extends up through the top wall of the chamber L. A helical compression spring 33 acts between the collar 32 secured to the external portion of the link 3 I, and the subjacent portion of the housing L, in the direction to force the sprocket wheel I2 upward against the corresponding portion of the sprocket chain I2, and normally maintain the parts in their positions shown. As the sealing edge g is pressed with increasing force against the sealing edge pawl A, in the course of the door locking operation, the torque required to rotate the shaft 1 increases. When this torque attains a certain maximum value, dependent upon the normal tension of the spring 35, that spring yields and .permits the lever 35 to turn in the counterclockwise direction, as seen in Fig. 3. As the sprocket wheel it thus moves downward, the portion of the sprocket chain running between the undersides of the sprocket wheels H and 3, straightens out more or less, with no transmission .to the gear I3 of the rotative movement of the gear N then occurring. The safety mechanism including the sprocket wheel l2 and spring '33 thus operates as a mechanical overload device permitting the rotation of the spindle I to stop without stalling the motor 8, when the resistance to further rotative movement of the corresponding spindle 3 corresponds to a predetermined sealing pressure.

If the motor 8 were to continue in operation after the lower run of the chain I2 straightens out, the sealing pressure would then be increased above the desired maximum. To'avoid this, the safety mechanism is adapted to interrupt the operation of the motor after a certain extent of compression of the spring 33 and down movement of the link 3!, less than that required to fully straighten out the lower run of the chain 52. Thus, as shown in Fig. 3, a second collar 34 on the upper end of the link 3| acts, when the latter is depressed, to give a down movement to the actuating arm 35 of a motor control switch Q, thereby opening said switch and interrupting the energizing circuit of the motor '8.

While the safety mechanism arrangement already described is effective to prevent excessive rotative movement of the spindle in the locking direction, it is not effective to prevent excessive movement of the spindle in the reverse direction, such as would occur if the termination of the unlocking operation of the motor 8 were dependent on action by an operator, who, for some reason, fails to stop the motor 8 at the proper time. As a protection against such overtravel of the spindle I in the unlocking direction, with its possibly injurious consequences, I have provided the shaft |4,'as shown in Fig. 2, with a threaded axial extension 40. A nut 4| on the threaded shaft 45, is connected to the actuating arm 42 of a control R, so that the latter is operated to interrupt the energizing circuit of the motor 3 after a certain number of revolutions of'the threaded shaft 45 in the spindle unlocking direction, and a corresponding movement of the I nut away from the housing L.

As those familiar with electric motors will understand, the energizing and control circuits for each motor 3, and the manner in'wh ich the corresponding switch Q and R are associated therewith, may take many'form's, and are dependent in part on the character of the motor By way of example, one circuit arrangement is illustrated diagrammatically in Fig. 4. In that arrangement, the motor 8 is shown as of the direct current type, and is energized for operation in the door locking direction when a relay switch winding 5| is energized and moves the associated armature 52 to connect the motor armature 36 of the field winding 8A and motor in series with one another and a source of current 50. In a similar manner, the motor '8 of Fig. 4 is energized for operation in the door unlocking direction, by the energization of relay switch winding 54, whereupon the associated 75 armature 55 is moved to connect the armature tlC'ahd current source in series with a second motor field winding 83.

As shown in Fig. 4, the relay winding 5|,is energized by the momentary closure of a normally open, manually adjustable control switch S, which has ,one terminal connected through a source of current 53 to one terminal of the winding 5|, while the other terminal of the winding 51' is connected to the second terminal of the switch S through the normally closed switch Q. Similarly, the-closure of a normally open control switch SA charges a relay win-ding 54 by connecting the latter in series with the source 53 and normally closed switch R.

The energization of the relay winding 5| closes a-so-called holding in circuit, by closing a shunt about the switch S, so that the reopening of the latter will not deenergize the winding 5|. Said shunt includes a normally open switch T closed by the relay armature 52 when the winding 5| is energized, and a normally closed switch UA, which is opened by the energization of the relay winding 54. The holding in circuit for winding relay 5| may be interrupted, and said winding deenergized, either by actuation of the switch arm 35 to open switch Q, or by the closure of the switch SA and resultant energization of the relay winding 54. A similar holding in circuit for maintaining the energization of the winding 54, is established when the armature 55 is energized to close the normally open switch TA and thereby establish a shunt about the switch SA, said shunt including the switch U, which is opened only when the winding 5| is energized. The relay winding 54, when energized, may thus be deenergized either by opening the switch R, or by closing the switch S and thereby opening the switch U.

As will be apparent, the switches S and SA and current sources 53 of Fig. 4, may be used in simultaneously energizing both the motor 8 shown in that figure, and the second motor 8 of the door machine. To that end, the parts S, SA and 53shown in Fig. 4, may be connected through conductors 56 to control and energizing elements for the second motor 8, which are duplicates in form and disposition, of the elements 50, 5|, 52, 54, 55, T, TA, U, UA, Q and R shown in Fig. 4.

The means shownin Fig. 2 for opening the switch R and thereby interrupting the door unlocking operation of the motor 8, are adapted for use under normal operating conditions in which door locking and unlocking operations are effected in regular alternation. \Vhen, as may sometimes happen, two door locking operations occur without an intervening unlocking operation, or two unlocking operations are effected without an intervening locking operation, the mechanism for actuating the switch R is rendered inoperative, and may be injured by the excessive movement which it then gives or tends to give the nut 4|. With the arrangement shown in Figs. 5 and 6, however, as with that shown in Figs. 7 and 8, the extent of each unlocking movement of each mechanism L is automatically controlled regardless of the order in which the locking and unlocking operations occur.

In the arrangement shown in Figs. 5 and 6, I employ a self=opening time switch SB, in lieu of the switch SA shown in Fig. 4, to start the unlocking operation of the motors 8. As shown in Figs. 5 and 6, the switch SB is a mercury switch, comprising an elongated mercury container, or envelope, supported-by a shaft SB journalled in a suitable support and provided with a handle SB by which the container may be angularly adjusted. Partition means 60 within the container divide the interior of the latter into two chambers BI and 62, one in each end portion of the container. A pair of contacts 65 ext-endinto the space BI and are adapted to be operatively connected by mercury in that space' when the container is turned-so that the space BI is filled with mercury and is above the space 62, as shown in Figs. 5 and 6. With the container in the position shown, mercury in the space Bl will drain into the then lower space 62 through a restricted drain passage 133, which opens to the space 6 I about midway between the two ends of the containers, and opensto the space62 adjacent the corresponding end of the container. The time required for enough of the mercury in the container to drain out of the space Bl through the passage 63 into the space 62, to break the previously existing mercury bridge between the two contacts 65, determines the length'of the period during which the associated motors 8 are then energized for operation in the unlocking direction. The next unlocking operation may be started by giving a half turn to the container so as to locate the space 62 directly above the space 6|. As soon as this is done, the mercury will begin to drain from the space 62 into the space 6|, through a restricted passage 64, which is a counterpart of the passage 63.

with the contact 66 and the other contact 65 is in engagement with the contact 61 when the parts are in the position shown in the drawings. When the'container is given a half turn, one contact 65' engages the contact 66, and the other contact 65' engages the contact 61. The switch SB may be connected into such 'a motor control and energizing circuit as is shown in Fig. 4, to replace the switch SA, in the manner shown in Fig. 5. No holding in circuit for the relay winding 54 is provided, with the arrangement shown in Fig. 5, since the relay winding 54 will be energized so long as the contacts 65, or 65, engaging the contacts 66 and 61, are connected by mercury within the switch container, provided that both switches R. and U remain closed. Each of those switches are connected in the energizing circuit of the winding 54, in series with the current source 53 and the contacts 66 and 61. The elimination of the holding in circuit for the winding 54 makes it unnecessary to provide a switch TA in the arrangement shown in Fig. 5.

The arrangement shown in Figs. 7 and 8 for automatically limiting the extent of unlocking movement, is like that shown in Figs. 1, 2, and 3, in that it makes use of a threaded rotating shaft included in each mechanism L. In the arrangement shown in Figs. '7 and 8, however, the safety mechanism including the threaded shaft, is automatically reset, so to speak, into the same initial condition, prior to each unlocking operation. As shown in Figs. '1 and 8, rotation of the shaft 14 in the door unlocking direction, rotates a vertically disposed safety mechanism shaft 12 through a bevel gear 10 carried by the shaft l4, a cooperating bevel gear 11, and a ratchet or analogous clutch 8!! connecting the gear 1| to the lower end of the shaft 12. The clutch 80 is provided to permit the shaft 12 to remain stationary while the shaft l4 rotates As shown, one contact 65 is in engagement in the door locking direction; The gears "and 11 are located in the housing chamber L andthe shaft 12 extends-upward through the top 'wall of that chamber. U a Y Secured to the upper end of the shaft 12,- is a top member 13- of a fly ball governor 13. Th'e latter comprises a lower collar 14 loosely-sun rounding the shaft 12, and raised and lowered by the governor weights as the rotation'ofthe shaft 12 is started and interrupt-ed. A bellcrank lever 15, pivotally supported at 16, comprises a horizontally disposed upper arm, with its freeend in engagement with the collar 14, so that the lever 15 is tilted about the horizontal pivot pin 16 as the collar 14 is adjusted longitudinallyjo'f the shaft 12. The second arm of the lever 15 'is generally vertical, and alongside'the shaft 12 and is formed with a guideway 11 for a mutilated nut element 18. The threadedend'of the latter .is moved into operative engagement with the thread on a finely threaded portion 19- o'f the' shaft 12, located below the governor 13. "'When the motion of the shaft 12 is interrupted, and the collar 14 moves downward, the lever 15 is tilted to move the nut member 18 out of engagement with the threaded portion 19 of the shaft 12. The threads on the shaft portion 19 ancl'nut .18

are so formed, that the rotation given the'shaft 12 in the unlocking operation, will move the-1 member 18 upward until a projection therefrom engages and actuates a control element, which, as shown, is the operating arm 42 of the switch R. The latter, in the form shown in Fig. 7,-is' mounted on top of the housing of the corresponding mechanism housing. As shown when the rotation of the spindle 12 isinterrupted, and

the governor collar 14 is lowered and tilts' 'themember 18 out of engagement with the threaded shaft portion .19, the member 18 moves downito the bottom of the guideway 11, under the action of gravity, which, if necessary, may be supplemented by the action of a bias spring. The safety mechanism is thus reset at the end of each door unlocking operation.

As will be apparent, instead of swivelling each locking bar on its corresponding spindle and threading the latter into a socket formed in a rigid portion of the door, the spindle may be swivelled in the door, and 1n threaded engagement with the locking bar, which is then adjusted bodily in the longitudinal direction of the spindle when the latter is rotated. An arrangement of this sort is shown in Fig. 9, wherein a locking bar supporting spindle EA is journalled in an unthreaded passageway through a door part DB, otherwise like the previously mentioned parts D and. DA. As shown, the spindle EA is held against longitudinal movement relative to the part DB, by collars E and E pinned on the spindle. The latter is formed adjacent its outer end with a threaded portion E", shown as somewhat larger in diameter than its main unthreaded portion, and the corresponding looking bar IA is normally in threaded engagement with said threaded portion E. In consequence, when the spindle EA is rotated, the locking bar IA is adjusted longitudinally of the spindle. As will be apparent, if in locking a door in place, the rotation of the spindle EA of Fig. 9 is in the same direction as that of the spindle E of the constructions previously described, the spindle EA should be formed with a right handed thread,

handed thread, assuming that in the door locking operation, the shaft I rotates in-the direction shownin Figs. 2 and3.

With the threaded connection between the locking bar and supporting spindle shown in Fig. 9; an. excessive extent of rotation of the spindle inlthe door unlockingdirection, will have no injurious consequences, if the partsare so arranged that the locking bar IA may move inwardly along the spindle EA, until it passes out of threaded has an internal diameter just large enough for the; movement therein of the threaded spindle portion E and cooperates with the latter to connection between the bar and, the spindle is interrupted.

While in, accordance with the provisions of the statutes, I have illustrated and described the best forms of embodiment of my invention now known to me, itwill be the, appended claims and'that insome cases certain features of my invention may be used to advantage without-a corresponding use of other features.

Having now described my invention, what I clainnasnew and: desire to secure by Letters Patent; is:

thespindle, said'locking bar being formed with an annular I guide portion surrounding said spindle portion and centering the lockmg, bar relative to the spindle, when said intermediate portion is within said socket.

2. In a self-sealing door, the combination with a rigid portion of the :door, of

Within said threaded socket and a spring-acting onsaidlocking bar in the direction tending to move thelatter outwardlyalong the length of the spindle.

CARL OTTO. 

